Navata Road Transport — collection of extra amount than the billed amount in navata transport patancheru

My way bill number are 081191, 081192, 081193 and total bill amount is 1482 rupees, but he collected 1600 rupees, as per his words collected extra 10 rupees for each bag(total 12 bags), total amount collected extra is 120 rupees and i asked him regarding this and told like it is loading and unloading charges.
if loading and unloading charges to be collected it should be on bill not to be collected unofficially